The present invention refers to a disposable bottle or container having a gradually collapsible, recovery-free, structure of its sidewalls.
More particularly, the disposable bottle according to the invention is provided with accordion-like sidewalls, which can be collapsed step-by-step as the internal content of the bottle is used up, so as to maintain practically constant the volume of air at the top of the bottle. At the same time, the volume of the bottle is reduced in proportion to its actual content, saving space in the places wherein the bottle or container is stored. Finally, when the content of the bottle is completely used up, the bottle has reached its minimum volume and can therefore be directly thrown away, without any further compacting operation, as is usually required for empty containers so as to reduce the bulkiness of the rubbish.
Bottles and containers of this general kind have already been proposed in prior art without, however, having provided technical solutions apt to be satisfactorily used for the above purposes. At present, a disposable bottle which actuallyxe2x80x94and not only in theoryxe2x80x94provides the positive features described heretofore is therefore still lacking on the market, for the reasons that will be explained in further detail hereinafter.
A first bottle of this kind proposed in prior art was, in fact, a bottle formed of a plastic material having substantially elastic properties at room temperature and shaped, for at least part of its height, as an accordion; each bellows element of the accordion (hereinafter simply indicated as xe2x80x9cfoldxe2x80x9d) was formed by opposed conical surfaces having the same width. This type of container was provided to house liquids that undergo a quick degradation upon contact with air as, for example, photographic developers. After having drawn a quantity of liquid from this bottle, and before closing it again, the accordion-like portion of the bottle had to be squeezed to an extent sufficient to permit the liquid content, still held therein, to reach the neck of the bottle, then reducing to a minimum level the quantity of air entrapped in the bottle. Due to the elastic properties of the bottle material and, above all, to the symmetric shape of each fold of the accordion-like structure, this operation must be accomplished each time that some liquid has to be drawn from the bottle, since said accordion-like structure has only one position of stable equilibrium, i.e. its extended position. The above described type of bottle is therefore not suitable to be used in applications wherein a frequent use of the bottle content is requested, as for example in the case of beverages.
Another type of collapsible bottle has therefore been proposed in prior art, wherein each fold of the accordion-like sidewalls of the bottle is provided with two positions of stable equilibrium, i.e. an extended position and a collapsed position, thanks to the fact that the two opposed conical surfaces forming each fold have a different width and the smaller surface can therefore be steadily housed, in a collapsed configuration, inside the adjacent larger surface. As the content of the bottle is used up, the consumer may cause the progressive collapsing of each fold, and the bottle steadily remains in the collapsed configuration, at least until an external force is applied to return the collapsed folds into the extended equilibrium position. An example of this second type of collapsible bottle is disclosed in U.S. Pat. No. 4,492,313.
Notwithstanding the above-described improvement, even this second type of collapsible bottle has however not reached a satisfactory industrial application, due to the fact that it still involves the significant drawback of a low resistance against the return of the collapsed folds to the original extended position, as hereinafter described.
This drawback is actually due to the fact that the stable equilibrium position of each fold of the accordion-like sidewalls of the bottle, in the collapsed configuration, has on an average, a rather low degree of stability. It is thus possible, at any time, to return the bottle from the collapsed to the extended configuration, by simply applying on the bottle a force of sufficient intensity in an appropriate direction, as it happens, for example, when a bottle is filled with a gassed liquid, or when it is overturned to pour its content, or in handling the same.
The above-described restriction of use in respect with gassed beverages is particularly unfavourable. In fact, it should be kept in mind that gassed beverages form an important share of products that could possibly and advantageously be packed in a collapsible container. The taste and the gas content of said beverages, even when the same are partly used up, could in fact be preserved for a long while.
This result, however, although expected in theory, has not been up to date achieved in practice. In fact, the gas pressure developed inside the bottle, once the same has been closed in a collapsed or partially collapsed configuration, is sufficiently high to return soon or later the bottle in a more extended or fully extended configuration, thereby forming in the bottle that empty space which purportedly should be avoided.
The same inconvenience, however, also happens when the content of the bottle is a flat liquid, especially a viscous one, or a solid particulate, each time the bottle is overturned for storing purposes or simply to pour its content. In this case, in fact, the weight of the bottle content pressing onto the top portion of the same is often sufficient to return the bottle to its extended configuration.
In EP-A 850 842 is disclosed a collapsible container wherein each of the bellows element is formed by opposed conical surfaces having the same width, so rendering impossible any stable collapsed configuration of the container. Moreover the indentations provided in one of said surfaces are non apt to regularly determine one specific and desired collapsed configuration of the bellows.
The object of the present invention is to thus supply a disposable bottle having a gradually collapsible accordion-like structure of its sidewalls, wherein each fold of said structure, once it has been collapsed, is provided with a high degree of stability, i.e. in the normal use and storage conditions, even with gassed liquids, it is substantially prevented from returning into an extended position (recovery-free).
This object is reached, according to the present invention, with a disposable bottle having a gradually collapsible structure, of the type in which the sidewalls of the bottle have an accordion-like structure comprising several adjacent folds, each fold being formed by two opposed surfaces of different width, characterised in that said fold-forming surfaces comprise blocking means apt to prevent the recovery of the fold, under a predetermined force, once the same fold has been collapsed for the first time.
In a first embodiment of the invention, said blocking means are obtained by providing that at least the smaller surface, of the two surfaces forming each fold, has an arched shape and that the convexity of said surface is directed towards the adjacent larger surface against which it collapses.
In a second embodiment of the invention, said blocking means are instead obtained by providing a peripheral groove on one of the surfaces of each fold and a co-operating matching rib on the other one of said surfaces.
According to a feature of the invention, one or more cylindrical annular sections are moreover provided on the bottle sidewalls, apt to interrupt the accordion-like structure thereof, to stiffen the bottle and prevent any possible ovalization of thereof during the collapsing action.